a. Field of the Invention
The present invention pertains to timing chain covers for V-8 engines and specifically to timing chain covers for high performance applications.
b. Description of the Background
The conventional timing chain cover Chevrolet small block and big block engines is a stamped sheet metal cover. In high performance applications, such as various forms of racing, there is a need to remove the timing chain cover to perform periodic maintenance or to adjust timing components, such as the cam timing.
In some racing applications such as drag racing, the harmonic balancer seal must be replaced after each race. In order to perform this service procedure, the entire conventional timing chain cover must be removed.
Racers may wish to adjust the various timing characteristics of the engine. For example, the timing marker is typically fixedly mounted to the timing chain cover. The sheet metal timing cover may not have locating features, such as locating pins, to accurately locate the cover to the block. Thus, when the cover is removed and replaced, the timing marker may not be in the exact location. Some racers may wish to more accurately and repeatably position the timing marker.
In another example, the cam timing may be adjusted by adjusting the cam gear at the top of the timing chain. The adjustable cam gear typically requires that the timing chain cover be removed so that the mechanic may have access to the gear. Removal of the timing chain cover, again, typically requires that the harmonic balancer be removed.
Further, the standard timing chain covers may not fit when double roller timing chains are used on the engine. Since the double roller timing chain is wider than the standard timing chain, the factory timing chain cover may need to have a spacer in order to accommodate the wider chain.
Standard timing chains for Chevrolet V-8 engines may not have an adjustment or slack remover that may be typical of other engines.
In some racing applications, an adjustable thrust bearing system may be placed between the timing chain cover and the cam gear to prevent the cam from riding forward during operation.
It would therefore be advantageous to provide a timing chain cover that provides repeatable location for the timing marker and allows for the slight adjustment of the timing marker. It would be further advantageous to provide a cover that allows for quick changeover of the harmonic balancer seal and access to the cam gear for adjusting the cam timing. It would be further advantageous to provide a timing chain cover that allows adjustment of the cam timing without removing the harmonic balancer.
The present invention overcomes the disadvantages and limitations of the prior art by providing a timing chain cover that comprises a frame that is permanently mounted to the engine block, and a removable cover that is accurately located to the frame. The removable cover may have a harmonic bearing seal retainer that can be accessed without removing the timing chain cover. Further, the timing marker may be precisely adjusted and even relocated for different sized harmonic balancers. The removable cover may contain a second cover that may provide access to the cam gear for adjusting the cam timing. Further, the removable cover may contain provisions for an adjustable thrust bearing to act against the cam gear.
The present invention may therefore comprise a removable timing chain cover for an internal combustion engine comprising: a frame fastened to the block of the engine; a removable cover fastened to the frame, the cover having a locating feature adapted to position the removable cover onto the frame, the cover having an o-ring seal about the periphery of the cover between the cover and the frame; a harmonic balancer seal retainer fastened to the removable cover adapted to retain a seal for the crankshaft of the engine, the harmonic balancer seal having an o-ring seal about the periphery of the seal retainer between the seal retainer and the removable cover; and a timing marker mounted on the removable cover and adapted to be mounted in at least two positions, the timing marker further adapted to be adjusted in position substantially about the axis defined by the crankshaft of the engine.
The present invention may further comprise a removable timing chain cover comprising: a frame fastened to the block of the engine; a oil pan seal holder fastened to the frame and adapted to hold a gasket between the oil pan seal holder and the oil pan of the engine; a removable cover fastened to the frame, the cover having an o-ring seal about the periphery of the cover between the cover and the frame; a harmonic balancer seal retainer fastened to the removable cover adapted to retain a seal for the crankshaft of the engine, the harmonic balancer seal having an o-ring seal about the periphery of the seal retainer between the seal retainer and the removable cover; a timing marker mounted on the removable cover and adapted to be mounted in at least two positions, the timing marker further adapted to be adjusted in position substantially about the axis defined by the crankshaft of the engine; a cam timing cover fastened to the removable cover and adapted to be removed while the harmonic balancer is mounted on the crankshaft of the engine, the cam timing cover having an o-ring seal substantially about the periphery of the cam timing cover between the cam timing cover and the removable cover; and a tensioning system mounted to the frame comprising a spring loaded tensioner and a fixed tensioner.
The advantages of the present invention are that access to various adjustable or replaceable components underneath or attached to a timing chain cover may be serviced or replaced quickly. Further, the o-ring seals between the components that are disassembled can be removed and replaced repeatedly without damage. The harmonic balancer seal may be replaced without having to remove the timing chain cover. In some cases, the cam timing can be adjusted without having to remove the harmonic balancer and complete timing chain cover. The timing marker may be adjusted both for different sized harmonic balancers as well as circumferentially to precisely adjust the timing.